CVE-2016-7472 in BIG-IP ASM
Summary
by MITRE
F5 BIG-IP ASM version 12.1.0 - 12.1.1 may allow remote attackers to cause a denial of service (DoS) via a crafted HTTP request.
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Analysis
by VulDB Data Team • 05/30/2019
The vulnerability identified as CVE-2016-7472 affects F5 BIG-IP Application Security Manager (ASM) versions 12.1.0 through 12.1.1, representing a critical remote denial of service flaw that can be exploited by unauthenticated attackers. This vulnerability resides within the HTTP request processing functionality of the BIG-IP ASM module, which serves as a web application firewall and security gateway for enterprise applications. The flaw manifests when the system encounters specially crafted HTTP requests that trigger an improper handling mechanism, leading to system instability and potential complete service disruption. This vulnerability directly impacts organizations relying on F5 BIG-IP appliances for web application security, as it provides attackers with a straightforward method to render critical security services unavailable.
The technical implementation of this vulnerability stems from inadequate input validation within the HTTP request parsing logic of the ASM module. When processing malformed or crafted HTTP requests, the system fails to properly handle certain request parameters or headers, causing the application to enter an inconsistent state that results in a crash or system hang. The flaw operates at the protocol level where HTTP request parsing occurs, making it particularly dangerous as it can be triggered through normal web traffic without requiring any authentication or privileged access. This type of vulnerability falls under CWE-129, which addresses improper validation of input boundaries, and represents a classic example of how malformed input can lead to system instability and denial of service conditions. The vulnerability demonstrates poor error handling practices where the system does not gracefully manage unexpected input patterns.
The operational impact of CVE-2016-7472 extends beyond simple service disruption, as it can severely compromise the availability of web applications protected by F5 BIG-IP ASM. Organizations using affected versions may experience complete service outages during exploitation attempts, potentially affecting hundreds or thousands of users depending on their application architecture. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet, making it particularly dangerous for publicly accessible web applications. From an attacker's perspective, this vulnerability provides a straightforward path to causing disruption without requiring specialized tools or significant technical expertise. The impact aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through exploitation of system vulnerabilities, and demonstrates how weaknesses in web application firewalls can be leveraged to compromise availability.
Mitigation strategies for CVE-2016-7472 primarily involve immediate patching of affected F5 BIG-IP ASM versions to the latest available releases that contain the necessary security fixes. Organizations should prioritize updating their systems to versions 12.1.2 or later, as these releases include the specific patches addressing the HTTP request processing flaw. Additionally, network administrators should implement temporary workarounds such as rate limiting, connection filtering, and implementing additional security monitoring to detect and block suspicious HTTP traffic patterns. The vulnerability serves as a reminder of the importance of maintaining up-to-date security patches and demonstrates the critical need for regular vulnerability assessments and security monitoring. Organizations should also consider implementing redundant security measures and failover mechanisms to maintain service availability during potential exploitation attempts. This vulnerability highlights the necessity of following security best practices including regular patch management, proper input validation, and maintaining comprehensive security monitoring to prevent successful exploitation of similar flaws in the future.